Fifty-two people were murdered in the tube terror attack on 7/7, over ten years ago, roughly the same number as those slaughtered in Orlando yesterday. But reasons why Islamist terror takes place were then much more contested. One version, held by some in the most prominent organs of the state – Parliament, the security services, the police, the civil service – was that it was a direct response to western foreign policy. Britain’s armed forces had been in Afghanistan since 2001, and in Iraq since 2003, only two years before 7/7 took place. It was the era of neo-conservatism.

It is a statement of the obvious that foreign policy can be a contributor to Islamist terrorism – or perhaps it would be better to say foreign affairs. The first British suicide bomber, Asif Sadiq, died in Srinagar in Indian-held Kashmir. He drove a car packed with explosives into an Indian army base in 2000, before those deployments of British troops abroad and before 9/11 had taken place. Britain had no real foreign policy engagement in Kashmir at all, and has not done so for three-quarters of a century. But the legacy of our disengagement from the one-time princely state was enough to drive a young man to kill himself and to massacre others.

The dispute over why Islamist terrorists act as they do divided the Conservative Party no less than it did those other institutions. A group of Tory Shadow Ministers (including Michael Gove, Pauline Neville-Jones and, on a lower rung of the ladder, myself) argued that the sum of the evidence was obvious: that such groups as Al Qaeda were part of a wider Islamist movement that hates, and wants to end, western liberal democracy altogether – and see it replaced by a system of pre-modern law, and which people are treated on the basis of religion rather than as equal citizens of secular states.

Ten long years on, it is striking how foreign policy as the be-all-and-end-all explanation of Islamist terror and extremism has faded away. And no wonder, since it has been comprehensively debunked. Debunked by the Danish cartoons row, which saw death threats issued against those who had drawn them and the papers that had carried them. Debunked by the Charlie Hebdo murders, a bloody response to illustrators who had drawn satirical illustrations of Mohammed. Debunked by the terror attacks in Belgium, whose military footprint abroad is tiny. And now, horribly, debunked by the atrocity in Orlando.

It is too early to know if Omar Mateen, the murderer in America, acted as a “lone wolf” killer or not. There is a pattern of Islamist terrorists first being identified as such but later turning out to have had links with terror groups abroad, and Mateen was reportedly investigated by the FBI twice. But it seems clear that the assault was an act of Islamist terrorism: Mateen had not only been subject to police enquiries but had apparently pledged allegiance to ISIS, the last during the terror attack itself. A picture is emerging of a terrorist charateristic of such terrorists: a “wild boy” separated from an ex-wife and living apart from others, in this case eking out an existence as a security guard.

Mateen was apparently entitled to carry a gun in the course of his work, and there will be questions about how he was able to pass security checks, given the police investigations, and wider ones about America’s gun laws and gun culture: after all, this is scarcely the first mass killing in that country in recent years. But it is the one that has claimed the most lives and one for which the apparent motive was unusual – and which has deep implications. Mateen deliberately targeted a gay bar. According to his father, he was angered recently by the sight of two men kissing each other in public.

The father went on to say that the attack had “nothing to do with religion”. By this, he doubtless meant that mainstream Islam does not sanction attacks on civilians. This is right. But in another sense it seems to have had everything to do with religion – that’s to say, with Islamism itself, which seeks to make religious law rather than secular democracy the governing principle. One report notes that a British-born preacher, Farrokh Sekaleshfar, recently urged the death of all gay people. “Death is the sentence. There’s nothing to be embarrassed about this. Death is the sentence,” he said. He was speaking just outside Orlando as recently as March.

We speak of culture wars. It does not usually occur to us as we do so that these can be real wars with real casualties. Orlando is the very worst of what can happen when two cultures indeed clash: the modern one of secular rights, of which gay rights are a part, and the pre-modern one of religious government, in which no rights exist save those that are divinely given. There are many examples in history of peoples having different conceptions of how they should be governed. But it is hard to think of two visions of human conduct that are so irreconcilably different and yet co-exist within the same countries.

Most of the time, they rub along together not exactly peacefully, but at least with an absence of conflict – obvious conflict, anyway. But now and again, the second assails the first by violence, and people die. Orlando is a warning to all of us, but perhaps most to the Left. Some equality provisions have come from the centre-right – it was a Conservative Government that introduced a Disability Discrimination Act – but their driving force (let’s face it) has usually come from the Left. Over the last 50 years, the Left has done more than the Right to own the slogan “Absolutely Equal”, and this conservative blog should acknowlege that this is so.

But if it is true that the Left has been foremost in pushing the cause of equality, including gay equality, it is also true that parts of the Left are in cahoots with those who would destroy it. A far left-Islamist alliance is struggling to dominate the Left, and has already chalked up some victories – including the presence within the Labour Party, one of the great public institutions of British life, of an anti-semitism so vicious that even its present leadership could not deny an official inquiry. Those who come for Jews today will come for gays tomorrow. This is a truth more comprehensively grasped on the Right of politics now than on the Left.

It was a Conservative politician who wrote of two nations “between whom there is no intercourse and no sympathy; who are as ignorant of each other’s habits, thoughts, and feelings, as if they were dwellers in different zones, or inhabitants of different planets; who are formed by a different breeding, are fed by a different food, are ordered by different manners, and are not governed by the same laws”. Disraeli was writing about “the rich and the poor”, but there is another application of his words from “Sybil”. If he survives this turbulent EU referendum, David Cameron wants to return to his One Nation project. The slaughter in America is a grim reminder of why we need it here.